Steam generator



Oct. 25, 1932.

H. J. E. BANcK STEAM GENERATOR Filed March 10, 1927 5 Sheets-Sheet l w: llllllii 1 1 'ITORNEY INVENTOR fi/swa IE fiA/vc f Oct. 25, 1932.

Filed March l0 1927 H. J. E. BANQK STEAM GENERATOR 5 Sheets-Sheet 2 INVENTOR /////v5 1/. EZ/M/C/f A'ITORNEY- Obt. 25, 1932.

H. J. E. BANCK 1,885,071

STEAM GENERATOR Filed Mar ch 10, 1927 5 Sheets-Sheet 5 //C A! H INVENTOR 5 #4: J5 BANG/r 9 F4 ATTORNEY Oct. 25, 1932 HIJ E. BANCK STEAM GENERATOR Filed March 10: 1927 5 Sheets-Sheet 4 INVENTOR Mm J5 nZi'm/c/r Patented Oct. 25, 1932 NITED. STATES P rsNT ome it HANS J. E. BANOK, or SPRINGFiELD, ILLINOIS; nssrenou To srnnverrntn BoILnIt 00;,

or SIERINGFIELD, ILLINOIS, A conronnrron or IL rnoIst,

' STEAM ennnnnron npplication filed March 1O, 1927. Serial No. 174,108.

My present invention'relates to steam generators and particularly to steam generators of the type in which a large portion of the heat is absorbed by direct radiatiomfrom a combustion chamber in 'whicha high temperature is maintained as by thecombustion therein of powdered coal; andnthe primaryobject of the present invention isto providev an advantageous disposition 'ofwater tubes absorbing radiant heat from the combustion chamber and from the heating gases which leave the combustion chamber while still at a relatively high temperature, and to combine with the water tubes steam collecting provisions and water clrculatmg provislons permisting'of the efiective use of the water tubes in absorbing heat and generating steam at the very rapid rate at which water tubesv are adapted to absorb heat by direct radiation from a combustion chamber in which a high temperature, is maintained and by direct contact with heating gases passing over the water tubes at high velocity andat high tempera tures; f I j I 1 Water tubes lining the walls of a combus-' tion chamber in which such high temperatures are maintained as are readily possible and desirable and indeed practically inevit able when powdered coal is burned with the aid of preheated combustionfainabsorb heat at a rate per square foot of heating surface very greatly in excess of'the average rate of heat absorption by the boiler heating surface of an ordinary'steam' generating boiler in which a substantial portion of the heat utilized is absorbed from the heating gases afterthe latter'have been cooled substantially below the combustion chamber temperature. For example, one of the constructions hereinafter-described as a preferred embodiment of the invention is' designed and adapted for the absorptionof heat at an average rate per square foot of heating surface approximately 20 times the average rate of heat absorption per square foot of bo ler heating surface in a water tube boiler operating properly filledv with water notwithstanding proper, simple and effective provisions for the rapid generation of steam in the tubes, To-this end-the water tubes are vertically disposed so far aspossible, and provisions are madefor normally maintaining a hydraulic head in all portions of the water tubes ebb- 3?- sorbin'gheat to any appreciable extent, and in addition provisions aremade for a sort of steam and water separating action at the top of each'water tube, to permit the ready es-: cape of the steam liberated in the tube while obstructing the discharge of water from the tube. In the practical carrying outrof the" invention, '1 provide a steam and water drum or other steam collector at a level well above the uppermost portion of the boiler in which any substantial heat absorption by the water tubes occurs and extendfthe vertical water tubes or uprising tubes or pipesreceiving steam and heated water fromthe water tubes proper to the'level of the steam collector and connect said tubes or pipes to the steam'col lector well above the water level in the generator in such fashion as to obstruct. or restrict the-passage into the steam collector of water carried upward in the tubes by the steam 'to'a level above the normal water'level of the' boiler. i

' Further specific objects of the invention are to combine with the steam generator;

utilizing available heat in the gases leaving the generator to preheat the combustion supporting air,"and for superheatingthe steam when, as is usually the case, it is desirable to utilize' a portionof the ,heat generated in the boiler furnace in superheating the steam. Another specific object of the inven-c tion isto provide my improved steam generator withieffective means for collecting the cinders or furnace dust. j

' The various features of novelty which characterize my invention are-pointed out withparticularity in the claims annexed to and, forming .a part of this specification. For a better understanding of theinvention, however, 'itsadvantages and specific objects attained with its use, reference'should be had to the accompanying drawings and'descriptive matterin'which I have illustrated and described preferred embodiments of my invention.

Of the drawings:

Fig. 1 is a side elevation with portions of the housing broken away and removed;

Fig. 2 is a sectional elevation'taken on the line 22 of Fig. 3;

Fig. 2A is an elevation illustrating a modified form of a portion of the apparatus shown in Fig. 2, elminating box D Fig. 3 is a rear elevation;

Fig. 3A is an enlarged rear view of a portion of the headers and the feed valve part ly in section;

Fig. i is a plan in section on the line 4. l of Fig. 2; I

Fig. 5 is a par ial section on theline 5-5 of Fig. 2;

'Fig. 6 is a partial section onthe'line 66 of Fig. 2;

Fig. 7 is a partial section taken similarly to Fig. 4 but on a larger scale;

Fig. 8 is a partial section on of Fig. 2;

Fig. 9 is a somewhat diagrammatic representation of a steam generator of modified form; and

Figs. 10, 11, and 12 are diagrammatic elevations each illustrating adifierent form of steam generator.

In the form of embodiment of my invention illustrated in Figs. 1 to 6,. A represents a'combustion chamber shown as rectangular in horizontal cross section, and having an upwardly inclined roof, and a hopper shaped cinder collector O at its bottom. B represents suitably disposed powdered coal inlet or burner nozzles, and G represents distribution boxes shown as running around the combustion chamber for supplying preheated air for combustion to the combustion chamber through ports G opening into the combustion chamber at suitably distributed points. The front, back, side and roof walls of the combustion chamber A incorporate or are lined by water tubes which form a large portion of the boiler heating surface.

As shown, the combustion chamber front wall water tubes D are vertically disposed and are connected at their lower ends to a horizontal header d. Each tube D is connected at its upper end through a suitable box like connector D to a roof tube D shown as connected at its upper end into a vertical box like header D The vertically disposed combustion chamber rear wall tubes E are connected at their lower ends to a horizontal header 0. Each tube E is connected at its upper end into one of the corresponding box like connectors D Each connector D is connected to the elevated horizontal steam collecting drum H through vertical tubes D which are connected at their lower ends to the connectors D and are connected at their upper ends into box like connectors D the 8-8 which are directly connected to the drum H by short horizontal pipes or nipples D".

In the construction shown in Figs. 1 to 6, inclined screen tubes d extend across the combustion chamber A above the hopper U. The upper ends of the tubes d are connected to the header (Z, and the lower ends of the tubes d which extend between the tubes E, are connected to a header d adjacent the header 0. V

The upper portions of the tubes E extend shown, a bafile G causes the heating gases to make a lower and a reverse upper pass in flowing from the combustion chamber outlet A to the heating gas outlet A from the,

chamber A The lower of these passes includes the upper ends of the tubes E, and the lower portions of the tubes G and G and of the sup'erheater elements K, while the upper portions of the elements K and of the tubes G and G and the lower portions of the tubes 1) are included in the upper pass through the chamber A As shown, the tubes G and G are connected at their lower ends into sectional headers g which are located at the bottom of the chamber A and are inclined to the horizontal, and receive water at their lower ends through nipples g from a horizontal header 9 At their upper ends the headers g are connected to the lower ends of inclined tubes G which are in effect eXtensions of the headers g, and as shown form a screen between the bottom of the chamber A and the top of a hopper shaped cinder collector O below thechamber A At their upper ends the tubes G are connected through connectors or short headers G to the lower ends of corresponding vertically disposed tubes G. The tubes G which line the rear wall of the chamber A are connected to short horizontal headers G At their upper ends the tubes G and G are connected into inclined sectional headers 93. The headers g are connected at their up per ends by tube extensions G into the head ers G The latter are connected by vertically disposed tubes G box like connectors G and short horizontal tubes or nipples G into the drum H at the opposite side of the latter from that to which the nipples l) are connected. The headers g and tubes G and the heat insulating material X which they support form the roof of the chamber A which is located a considerable distance below the drum H. V I

Each side wall of the combustion chamber A is lined or formed in part by a vertically disposed row of tubes F.v The various tubes F at each side of the boiler areconnected at their lower ends into a correspondinghorizontal lower header F and are connected at their upper ends into'a corresponding upper header F Advantageously, as shown, the headers F are less acutelyinclined to the horizontal than are the tubes I) and cross the latter.

This leaves the connector boxes D? at the sides of the boiler accessible without complicating the housing at the side edges of the roof of the combustion chamber. Each header F is connected at its upper end l a bent pipe F into the corresponding end 7 of a horizontal drum FE alongside of and'at the rear of the drum HQ The header]? is connected to the drum H by a series of short horizontal pipes or nipples F The side walls of the chamber A are each lined by a row of vertically disposed tubes FA; The

tubes FA at each side of the chamber A are connected at their lower ends to an inclined i header FA alongside'the headers g and eX- tensionsG thereof, and at their upper ends the tubes FA in each row areconnected to a sectional header FA? alongside the headers g and the tube extensions G thereof. Atits 7 lower end each header FA is connected by a vertical nipple FA to thewaterdrum or header Each header FA isconnected its upper end by a vertically disposed pip'e FA box-like connector FA} and horizontal nipple FA? into the drum H. The nipples F extend between thetubes G", andthe header F is located at the rearof the tubesGh The headers (Z 6, F, andg are supplied with water through down-comer piping external to the boiler housing comprising a vertically disposed pipe I at each rear cornerof the boiler. Eachpipe I has a lower branch pipe, I connected to the adjacent ends of the headers (Z and e, a second branch pipe I connected to the adjacent end of the corresponding header F, and a branch I connected to the adjacent end of theheader 9 The upper ends of the pipes I may be connected directly into the drum H, but'l prefer to connect those pipes into a smaller drum or header 71, shown as located directly beneath the drum H and connected to the latter by a the corresponding branch 1*. j v seals thus provided practically eliminate all possibility of water hammer incase the water row of nipples or short vertical tubes H The feed water supply connections J may also'be connected into the ends of the drum- H but preferably are connected into the ends of the header h. In the form shown, the connection to each end of the headers h-of an elbow fitting forming the portion of each pipe 1 directly connectedito thefheader h,

" and each branch I is shaped toprovide a water sealed outlet from the feedva-lve J" through which each pipe J is connected to The water level in the boiler falls below the header 7, as it may, without any serious consequence.

The header H may advantageouslybe provided with perforated or slotted bafiles H in, front 'of the nipples'D and G Ffiz'and FA to minimize water turbulence in the drum H, and to restrict the amount of moisture carried out of the drum with the steam through the header steam outlets H To avoid disturbances with fluctuating water levels, a perforated baflle H is advantageously located in the drum H above thefnipples H. The header H is shown as provided lower water level gage column LA. is con-' nected into one of the pipes I.

The boiler as a whole is supported by sus pension devices from external structural girders or beams M which may be carried by the boiler house columns (not shown). As shown, the steam collector H s supported by suspension straps M, and eachcollector box D is supported by an individualsuspension link M j each junction lQOX D issupported by two suspension links M each of the headers G is supported by one or more suspension'linkslll and sus ension links'are ro-" 7 vided for the connection boxes FA and head e'rs F The'headers F are also suspended by suitably disposed links M The super heater headers "are shownas supported by straps" M from the collector H. With the described arrangement, the boiler water tubes and connectors are divided into suitably small sectional units individually suspended so that relative contraction and expansion of the parts of the boiler may occur without sub- 7 ecting any portion of the structure to objectionablestrain. With all portions of the walls of the combustion chamber A and convection heating chamber A linedby or incor- Y porating water tubes, as described, the boiler housing X can. be relatively lightin weight [and inexpensive, and may be wholly or largely supported by the water tubes and connectors without likelihood of serious heat radiation losses, or of obj ectionableair or gas leakage into or out oft-he interior of the boiler; One suitable form of housing X illustrated in Fig. '7, comprises tile X fitting against the outer sides ofthe water tubes, and a'packing X of lrieselguhr or. the like between the tile X and an'exoernal metal sheathing;

& Portions of the watertubes and connector boxes and headers may be covered by refrac-.

tory material where it is desirable to minimize the heat absorption to prevent steam generation which might objectionably interfere with the water circulation, and to protect connector boxes and headers against possible overheating. Thus, as shown, the surface portions of the tubes D exposed to radiant heat from the combustion chamber A are reduced by the use of housing forming tiles X which lit against the or portion of the surfaces of the tubes. The tubes or nipples G and headers G are advantageously completely enclosed by refractory material, and

the undersides of the sectional headers 9 are advantageously covered by tiles, refractory cement or the like. In general, also, all of the connector boxes exposed to high temperatures are covered by tiles or other refractory material, and the portions of the headers F and which otherwise would be exposed at the interior of the combustion chamber are covered by refractory material. Advantageously, also, the portion of the boiler structure proper above the chamber A is enclosed by heat insulating material as shown so that the headers 7L and K and l 2 are en closed in a chamber A at opposite sides of which the tubes G and D are located.

The most effective use of the type of steam generator illustrated in Figs. 1 to 6 particularlyin generating steam at the higi pressures now coming into use, requires that the heating gases should leave the boiler proper through the outlet A at a temperature which is many hundred degrees above that of the atmosphere. To recover the available heat in the gases leaving the boiler proper any usual or suitable waste heat device as an air preheater or feed water heatingeconomize-r, may be employed, and any such device may be located with advantage in the space immediately above the combustion chamber. In burning powdered coal all of the available heat in the gases leaving the boiler proper may advantageously be used in preheating air for combustion, and in the construction shown in Figs. 1 to 6, N represents an air preheater for this purpose.

The air preheater N may be of any suitable type, and as conventionally illustrated, is of the well known plate or flat tube rccuperator type, with the air passages in the preheater leading from an air inlet 1 to an air outlet N The heating gases enter the gas passages of the preheater from a chamber 1 the bottom wall of which may be formed in large part by the portion of the boiler housing supported by the tubes D and the heating gases away from the air heater to a stack, or, more usually, to a draft inducing; fan through the top gas outlet N The air ordinarily suppl ed to the preheater inlet N by a forced draft fan (not shown) passes from the preheater air outlet N through a conduit N located at the front of the boiler and discharges at its lower end through branches N and N to the air distribution boxes 0 of which two are shown located one above and the other below the burners B. The amount of preheated air supplied to the combustion chamber above and below the burners B may be suitably regulated as by means of dampers N The location of the air preheater above the combustion chamber as shownin Figs. 1 to 6, obviously economizes space and cheapens the cost of construction and improves the operation by simplifying and shortening the air and gas passages. Furthermore, this disposition of the waste heat apparatus is advane tageous as portions of the boiler housing are utilized as a part of the air preheater housing, and heat radiated upward from the roof of the combustion chamber, for example, is in large part recovered in the air heater.

In burning powdered coal, particularly in urban power houses, it is highly desirable that the discharge of cinder dust into the atmosphere should be reduced to a practical minimum, and in the operation of any powdered coal burning boiler furnace provisions must be made to avoid cinder accumulations interfering with the operation of the furnace. With the construction shown in l to 6, the cinders are largely eliminated from the gases before the latter reach the reheater outlet N and the cinders settling out of the gases may be easily disposed of. A large portion of the cinders formed are directly l'w ceived in the dust collector 0, from which they can be removed in any usual or suitable manner. The cinder dust settling out of the gases in the chamber A are largely received in the collector O. The latter is advantageously provided with a door 0 for the discharge of the cinders collected, and to permit accessto the chamber A and the removal of superheater elements K and adjacent tubes G when replacements of such elements and tubes are necessary. To permit of ready entrance into the chamber A one or more of the nipples G may be omitted. The omission of some of the nipples G connected to any one header G will not interfere materially with the desired circulation since the remaining; nipples will supply all of the water which needs to be supplied to that header. It is obvious that cinders or furnace dust pilingup on the headers 1 may be blown. by ordinary soot blowers (not shown) into the combustion chamber A, in which case they enter the cinder collector O or into the collector O. Cinders accumulating on the balile G or con nector boxes D may be blown into the chamber A AD and AMD are access doors adapted for inspection and cinder removing purposes for the collector D and the headers, respectively. Cinders collecting'in the chamber N may be discharged from the latter from time to time through clean-out openings normally closed by doors N opening into pipimportant practical advantages.

be employed, I have not I sary to iliustrate finCldQSCllbG these features of the construct on in detail. In general, how- I ever, the nozzles B andports C are arranged to openinto the combustion chamber inthe spaces between the tubes D, E, or F lining the verticalwalls of the chamber; Aol van.- tageously, with the particular. combustion chamber arrangement employed'in the con? struction shown in Figsl to 6, the portion of the air boxes C at the sides of th-eco'mbustion chamber slope downward from thetront to the rear of the combustion chamber.

The general mode of operation contemplated of the'apparatus shown in Figs. 1 to 6 will be fairly apparent. from what has "already beensaid.v Fuel and preheated air for combustion are supplied to the combustion chamber, in regular operation, to provide the heat required, and to insure e-fiicient combustion and the maintenance of asuitably high combustion chamber temperature. The maor portion of the heat HtlllZQd; in the generalyirom the combustion chamber by the tubes 1 D, (1, D F, and E. The heating gases issuproper through the outlet A give up their available heat to theair supporting combuse;

tion as the air and the heating gases pass hrough the air preheater N. Theheat-absorbing surface of the boiler proper is highly eliectivaand the average rate of heat absorption per square foot of boiler heating surface may Well be twenty times that of a boiler operating at normal rating. Such a radical increase in capacity as comparedwith ordinary boiler practice possesses' obvious and cient means as described for recovering available heat from the heating gases leaving the boiler proper, the over-all eliiciency of the improved steam generator may be relatively high. 7

The practical effectiveness of my improved steam generator with the absorption of heat by the boiler heating surface which is not only possible but desirable, dependsin large part upon the vertical disposition of the tubes absorbing heat at a rapid rate and on the fact that the water in the portions of the tubes .ab so-rbing heat at a rapid rate is under a substantial hydraulic head, and on the fact'that the tubes are connected into thelcirculating system'in such manner that the rapid flow of as steam through and out of 1thevtubes does not thought it necess- .preventthe'gportions fot the tubes absorbing heat atajrapidflratefrom being substantially filled with water at all times; The vertical dispositioniot.theheat absorbing'tubes is desirable {because the frictional. resistance to the flow 'ot a turbulent mixture of water and steam is much less in a vertical tube than in a tube sufficiently inclined to the vertical Ito concentrate-the steam in bubbles or bodies in contact with the roof ofthe'tub'e passage, and a reductionin suchirictional resistance facilitates the escape of the steam generated and theinflo-waot the waterreplacing that evaporated. This desirable reduction in fric tional resistance'to flow invertical tubes tends to an undesirably rapid discharge of water from-the tubes. This tendency is minimized in accordance withthe present invention in part .by the hydrauliciheadimpressed on the Water inthe portions of thetubes absorbing heat at a rapid rate, and in part by the steam and water separating action, and fiow rrestricting effectlof theconnections between the upper ends of the tubes and thedrum H. The connector boxes D F4,G8 and FA? are "located above the normal water level and are connected to the drum I-I 'by'horizontal niption ot-steam is radiant heat absorbed'direct- P The abrupt ,changein thedirection of the flow of water and steam which enters the c011 nector boxes and. passing from the latter into the drumH restrictsthe flow and makes the steam pressure somewhat higher in the con nectors than in the' drum H. This pressure difference tends to the 'maintenance of a steam space in the connectors and the upper ends of the tubes connected thereto, and it is to be noted that, this tendency is much larger with a heavy boiler load when it is'most help ful, than when the boiler load is light...

' Further, when water enters the connector bores it ordinarily enters in waves or recurring jets and with considerable velocity and impinges more-orless violently against the top of thewalls otthe connectors. This tends toseparate the steam and water, and

to facilitate the'return ofthewater into the tubes, even though the upper ends of the latter are filled with a. seething mass ofsteam and water. From the foregoing, it will be A reduction in the amountof water carried into the steam collector. H reduces the amount of water unnecessarily moved through the tubes in which steam is generated, and while the restricted discharge into the header H tends of itself toreduce :the flow of water observed that the drums H andiaconnector f i boxes D F G and FA and nipples D into the lower ends of the tubes, the relatively great elevation of the header H above the lower water headers, and the fact that the down-comer piping l is external to the boiler proper so that the water is cooled rather than heated in passing through this piping insures an ample feed of water to the lower ends of the tubes. V

The improved boiler construction is characterized by numerous and more or less readily apparent advantages in construction and arrangement which facilitate inspection, tube replacemel'its and other repair and maintenance operations; The entire boiler may be easily drained, as by means of a suitable blowoff connection to the header 6. The water storage capacity of my improved boiler may be relatively small, since appreciable fluctuations in the boiler water level may occur without any appreciable interference in the regular operation of the boiler. While I contemplate that normally the water level of the boiler will be between the steam and water inlets to and below the water outlet from the drum H so as to be indicated by the water gage glass L, the operation of the boiler will be perfectly safe and substantially satisfactory if the water level falls so far that the water level gage column LA is only partly filled with water. This is an indication of the fact that with proper steam and water separating provisions at the'tops of the tubes, the drum H need not serve as a steam and water drum, but only as a mere 1 steam collector or header.

It is obvious that many changes in the de tails of construction illustrated in Figs. 1 to 6 may be made. For example, the connector boxes D may be omitted, the tubes D and E then being extended to'the connectors D as shown in Fig. 2A. It is apparent also that the general advantages of the invention may be obtained with boiler organizations differing materially in general form and appearance from that illustrated in Figs. 1 to 6, and in Figs. 9 to 12 inclusive, I have illustrated in a somewhat diagrammatic manner some of the modifications which may be employed. The boiler shown in Fig. 9 comprises a combustion chamber A with water tubes DA and EA at its front and rear sides. The water tubes DA are connected at their upper ends by inclined tubes DA to connection boxes DA and the tubes EA are connected by oppositely inclined tubes EA to connection boxes EA The boxes DA and EA are located at the opposite side of the drum H, and are connected to the latter by nipples, as are the boxes D and G in the construction first described. The tubes EA and DA cross one another, and with the portion of the boiler housing X supported by these tubes form the roof of the combustion chamber A As shown, there is a bank comprising several rows of tubes EA, and the heata second bank of vertically disposed watertubes GB. As shown, the chamber A including the tubes EA and GB, and elements K,'is not battled, so that the heating gases make a single horizontal pass over these tubes and elements. As shown, the upper ends of all the tubes EA are connected tothe drum H through the headers EA tubes EA, and bones EA while the upper headers GB for the tubes GB are connectedto the drum H by uprising pipes GB boxes G13 and horizontal nipples or tubes G13 TA represents the down-comer water piping connecting the drum HA to the headers or water drums DA and EA to which the lower ends of the pipes DA and EA are connected. The headers GB to which the lower ends of the tubes GB are connected receive water through tubes or nipples GB from the headers EA In Fig. 9, the powdered coal burner nozzles BA extend into the top of the combustion chamber through the spaces between the tubes EA and DA. T have not thought it necessary to illustrate in Fig. 9 the arrangement for supplying combustion supporting air to the combustion chamber, nor to illustrate the water tubes which would ordinarily be provided to cool the side walls of the combustion chamber A".

In the construction shown in Fig. 10, the combustion chamber A is lined at its front and back sides by tubes DB and EB, intermediate portions of which are inclined to the vertical to conform to thetapering shape of the upper portions of the combustion chamber. The heating gases leaving the combustion chamber A make three passes across a bank of vertically disposed tubes GO located in the convection heating chamber A of the boiler, G and G representing gas deflecting baffles. The heating gases pass from the outlet A of the chamber A into an economizer N13 and from thence into an air heater NA having a stack outlet connection NA. The tubes GC are connected at their lower and upper ends to inclined headers GO and GC respectively, and as shown, the upper ends of the tubes EB are connected into the upper ends of the headers GC The upper ends of the latter are connected to the steam and water drum H through connector boxes G0 and G0 at the opposite sides of the drum H and tubes GC and G6 The upper ends of the tubes DB are connected into the connectors G6 1B represents the down-comer piping supplying water passes from the feed water header h to the water drum EB beneath the tubes EB and directly connected to the latter, and connected to the lower ends of the tubes DB through screen tubes DB. The piping TB also supplies water to the tubes GO. 0

' associated tubes and piping practically iden-' cal with the corresp'ondingparts of the boiler shown-in Fig. 10 except for the omission of represents a cinder collector at the bottom of the chamber A, O" a cindercollector atthe "bottom ofthe chamber ri fi'and a cinder collector at the bottom of the economizer'NB. In rig. llfI have shown a doubleended boiler each section of whichcomprise's a combustion chamber A and a chamber A end the screen tubes and the consequentchanges in the form of the water supply piping. In Fig. 11 also the connector boxes CC and tubes GC are. omitted, the connector boxes GC for the two sections of the boiler being at opposite sides of the common drum II. In Fig. 11 the two chambers A 9 which "are placed back to back are separated to provide space for a waste heat device NC receiving heating gases from both chambers A The device NC may be an economizer, an air preheater, or may comprise separate economizer and air preheat er, sections. The boiler shown in Fig. 11 is practically identical with the boiler shown in Fig. 10, and need not be further described. p

The capacity of the'apparatus illustrated for operation at high ratings and with high combustion chamber temperatures, and the comparative ease with which cinders'andfurnace. dust may be collected and disposed of make the invention of especial importance for use with powdered coal firing; It will be apparent, however,'that the apparatus hereinbeiore described is well adapted for use,

practically without change, with oil or. gas firing; and the general principles of the invention may be used with advantage in steam generators heated by the combustion of a solid fuel bed, and in Fig. 11 I have shown I stclrer mechanisms Q for feeding coal onto a fuel bed supported by stoker gratesQ, at the bottom of the combustion chamber A.

In the relatively simple and compact form of the invention shown in Fig. 12, the'tubes DC at the front side of the combustion chamber A extend upward above the combustion chamber to the level of the elevated drum, H, to which they. are connected, connector'boxes DC and horizontal nipples between said boxes and the drum H. The vertical tubes EC at the rear of the combustion chamber are connected at their upper ends by unction' boxes EC to the tubes ECtwhich line the A are in communi'cationthrough the spaces between the tubes EC below an inclined bafiie G whichcauses the heatinggases to'malre, two passes across the vertical bank of tubes GE in the chamber A The upper ends of the tubes GE are connected to headers GE,

and the latter are connected to the connection boxeSEC through tubes or nip l T e ing gas outlet A from the chamber A opens through the roof of the chamber,

the escaping gases traversing the tubes. GE

A .row of tubes GE line the rear wall ofthe' chamber A The tubes 'FC lining the side walls of the combustion chamber A and the convection jheating chamber A are connected at their upper ends into inclined headers FC. The latterfare connected by bent pipe portions FC into-headersFC at the H by horizontal nipples. Down-comer'pipopposite side of the drum-H from thefconnection boxes DC, and connected to the drum ing IC from the feed water heater drum h is connected by suitable branches into the lower headers to which the tubes FC,.EC, and GE are respectively connected. Thehead- EC are connected, supply water to the tubes DC through thescreen tubes DC extending acrossthebottom of the combustion chamber A v While in accordance with the provisions of the statutes, I have illustrated and described the bestforms of embodiment of my'invention now known to me, it will be apparent to those skilled in the art that changesmay be made inthe forms of the apparatus disclosed without departing from the spirit of my invention as set forthin the appended claims, and that in some cases certain features of my invention may be used to advantage without a corresponding use of other features.

Having now described my invention what I claim as new and desire to secure 'byLetters Patent is:

1. In a steam generator adaptedfor operation at ratings greatly in excess of its nominal rating, the combination with vertically disposed water tubes arranged to absorb radiant 'heat from the combustion chamber of the generator 1n amount suflicient to generate the maj or portion of thesteam generated, steam and water separating means located at a level substantially above the heat absorbing portions of said tubes including a steam receiving means and conduit connections between the last mentioned means and said tubes arranged to restrict the escape of steam and water into said receiving means from said water tubes ers EC to which the lower ends of the tubes and to return to the upper ends of the latter 1 much of the water entering said connections from said tubes, and separate water return connections extending from said receiving means to the lower ends of saidtubes and-1d catedout of heat absorbing relation with said chamber whereby said heat'absorbing tube (ill portions are normally filled' with water under an appreciable hydraulic head.

2. In a steam generator adapted for opera tion at ratings greatly in excess of its nominal rating, the combination with a combu tion chamber having vertical side walls and an inclined roof portion, means for burning fuel at high temperatures in said combus tion chamber, a multiplicity of radiant heat absorbing water tubes lining the walls and roof of said combustion chamber, substantially all of said wall tubes being vertically arranged, a steam and water drum positioned at a level substantially above and separated from said combustion chamber, vertically arranged tubular connections extending upwardly from the upper ends of said radiant heat absorbing water tubes, and conduit elements con necting the upper ends of said tubular connections to said drum and arranged to prevent an undesirably rapid discharge of water from said tubular connections into said drum.

3. In a steam generator adapted for opera tion at ratings greatly in excess of its nominal rating, the combination with a combustion chamber enclosed by vertical walls and an inclined roof, means for burning fuel at high temperatures in said combustion chamber, a multiplicity of radiant heat absorbing water tubes lining the vertical walls and roof of said combustion chamber, substantially all of said wall water tubes being vertically ar ranged, a horizontal steam and water drum positioned substantially above and separated from said combustion chamber and arranged out of contact with said heating vertical tubular elements extending upwardly from the upper ends of said Water tubes in said combustion chamber, and means connecting said tubular elements to said steam and water drum preventing an undesirably rapid discharge of water from said tubular elements into said steam and water drum, said means comprising horizontal conduits connected to said drum above the water level therein and chambered members of greater internal cross section than said elements and conduits connecting the latter to said elements.

4. In a steam generator adapted for operation at ratings greatly in excess of its nominal rating, the combination with a combustion chamber enclosed by vertical walls, means for burning fuel at high temperatures in said combustion chamber, a multiplicity of radiant heat absorbing water tubes li ing the vertical walls of said combustion chamber, substantially all of said water tubes being vertically arranged, a second chamber laterally disposed relative to said combustion chamber, and connected thereto for the passage of heating gases at high temperatures therebetween, a multiplicity of water tubes in said second chamber arranged in the path of flow of said heating gases, substantially all of said last mentioned tubes being vertically arranged, a horizontal steam and water drum tubular elements extending upwardly from the upper ends of said water tubes in said combustion and second chambers, and conduit means connecting said tubular elements to said steam and water drum and arranged to prevent an undesirably rapid discharge of water from said tubular elements into. said steam and water drum.

5. In a steam generator adapted for operation at ratings greatly in excess of its nominal rating, the combination with a combustion chamber enclosed, by vertical walls, means for burning fuel at high temperatures in said combustion chamber, a multiplicity of radiant heat absorbing water tub-es lining the vertical walls of said combustion chamber, substantially all of said water tubes being verticaly arranged, a second chamber laterally disposed relative to said combustion chamber, and connected thereto for the passage of heating gases at high temperatures therebetween, a. multiplicity of water tubes in said second chamber arranged in the path of flow of said heating gases, substantially all of said last mentioned tubes being vertically arranged, a. horizontal steam and water drum positioned substantially above and separated from said second chamber and. arranged out of contact with said heating gases, vertical tubular elements extending upwardly from the upper ends of said water tubes in said combustion and second chamhere, means connecting said tubular elements to said steam and water drum and horizontally arranged to prevent an undesirably rapid discharge of water from said tubular elements into said steam and water drum, and external pipe connections from said steam and water drum to the lower ends of said water tubes.

6. In a steam generator adapted for operation at ratings greatly in excess of its nominal rating, the combination with a combustion chamber enclosed by vertical walls, means for burning fuel at high temperatures in said combustion chamber, a multiplicity of radiant heat absorbing water tubes lining the vertical walls of said combustion chamber, substantially all of said water tubes being vertically arranged, a second chamber laterally disposed relative to said combustion chamber, and connected thereto for the passage of heating gases at high temperatures therebetween, a multiplicity of water tubes in said second chamber arranged in the path of flow of said heating gases, substantially all of said lastmentioned tubes being vertically arranged, a horizontal steam and water drum positioned substantially above and separated from said second chamber and arranged out of contact with said heating gases, vertical tubular elements extending upwardly from the upper ends of said water tubes in said" combustion and second chambers, a-plurality of connector boxes connected to the upper ends of said vertical tubular elements, and

conduits connecting said connector boxes to said steam and water drum.

7. In a steam generator adapted for operabeing vertically arranged, a second chamber laterally disposed relative to said combustion chamber, and connected thereto for the passage of heating gases at high temperatures therebetween, a multiplicity of water tubes in said second chamber arranged in the path of flow of said heating gases, substantially all of said last mentioned tubes being vertically arranged, a horizontal steam and water drum positionedsubstantially above and separated from said second chamber and arranged out of contact with said heating gases, vertical tubular elements extending upwardly from the upper ends of said water tubes in said combustionand second chambers, a plurality of separate connector boxes connected to the upper ends of said vertical tubular elements, and horizontal tubular conduits separately connecting said connector boxes to said steam and water drum above the normal water level in said drum.

8. In a steam generator adapted for operation at ratings greatly in excess of its nominal rating, the combination with a combustion chamber enclosed by vertical walls, means for burning fuel at high temperatures in said combustion chamber, a multiplicity of radiant heat absorbing water tubes in said combustion chamber, a second chamber laterally disposed relative to said combustion chamber and connected thereto for the passage of heating gases at high temperatures therebetween, a multiplicity'of water tubes in said second chamber arranged in the path of flow of said heating gases, a steam and water drum positioned at a level substantially above and separated from said combustion and second chambers, tubular connections between said water tubes and said drum, said connect-ions being arranged to prevent an undesirably rapid discharge of water from said water tubes into said drum, a feed water supply connection to said drum, an external downcomer pipe connecting said supply connection to the lower ends of said water tubes,

and a water seal incorporated in said supply connection. a

9. In a steam generator adapted for operation at ratings greatly in excess of its nominal fmang, the combination was stamens,

ti'o'n' chamber enclosed by vertical walls, means forburning fuel at high temperatures iii-said combustioiijchambr, multiplicity of radianthat absorbing water esteem sa d combustion ehambeasecond chamber-1% wil -dama ed relative w saidflc'ombusti'on chamberandconne'ct'ed thereto a for the p s; sage sf. heating ases athig-li' temperatures therebetween, mnapntay of was tests in said secona chamber arranged in the path of new of said heating gases,a steam and water drum positioned at a level substantial 1y above and separatedrrom saidcoinbiistion and-second chambers, tubular Corina: tions betweensaidwater tubes and'said drum and arranged top'reve'iit an undesirably rap id discharge of water from said water tubes iiito said drum, plurality of 'superhater tube elements verazsan amng d in matt ondj hamber in the path offiow of said heat ing gases, and means connecting said was heater elements to said steam and water v drum, I a H 1O. I n' a-steamgenerator adapted for operation-at r'ating's'gre'atly n excess" of its I inal rating, the combination with a c'oi'ribus tion chamber having vertical side walls and an inclined roof portion, of means for burning fuel in suspension at high temperatures in said combustion chamber, means for sup: plying preheated air to spaced points in said combustion chamber, a multiplicity of radiant heat absorbing water tubes lining the walls and roof of'said combustion chamber,

a third chamber above said combustion cham her and laterallydisposed relative to said steam and water drum and said second chamber and connected to the latter for the passage ofheating gases therefrom, an air preheater located in said third chamber, and a conduit connecting said preheater to said preheated air supply means.

11. In a steamgenerator adapted for operation at ratings greatly in excess of its nominal rating, the combination with a combustion chamber having vertical side walls and an inclined roof portion, of means for burning fuel in suspension at high temperatures in said combustion chamber, a multiplicity of radiant heat absorbing water tubes lining the Walls and roof'of said combustion chamber, asecond chamber laterally disposed rel= ative to said combustion chamber and con neoted thereto for the passage of heating gases at high temperatures therebetween, a multiplicity of vertically arranged Water tubes in said second chamber, bafile means in said second chamber providing a serial flow of heating gases over the lower and upper portions of said Water tubes, a steam and Water drum ositioned substantially above and separated from said second chamber, tubular circulation elements separately con necting said steam and Water drum to the upper and lower ends of said Water tubes, a third chamber above said combustion cham-' her and laterally disposed relative to said second chamber and connected to the latter for the passage of heating gases therefrom, a heat exchange device located in said third chamber, dust collectors located in the lower ends of said combustion chamber and third chamber, and a conduit means connecting said dust collectors.

Signed at Springfield, in the county of Sangamon, and State of Illinois, this 5th day of March, A. D. 1927.

HANS J. E. BANCK. 

